1. Field of the Invention
This invention relates to an image reading apparatus for reading originals such as documents and photographs, and particularly to an image reading apparatus suitable, for example, as a scanner for computer input for converting read information into digital data and outputting it to a computer.
2. Related Background Art
Image reading apparatuses of this kind have heretofore been widely used as means for reading image information on an original such as a print or a photograph, and outputting it to a processing apparatus such as a computer.
FIGS. 6 and 7 of the accompanying drawings schematically show an image reading apparatus according to the prior art.
As shown in FIG. 6, the image reading apparatus SC100 is provided with a box-shaped frame 111, an original mounting glass table 100 disposed on the upper surface thereof, and an openable and closable door type original cover 112 disposed on the original mounting glass table 100, as main external appearance portions.
When reading an original, an original P is first placed on the original mounting glass table 100, whereafter the original cover 112 is closed to thereby press the original P on the glass plate. Next, a reading unit (scanning member) 115 (indicated by broken lines) provided in the frame 111 scans parallel to the plane of the glass plate to thereby read an image on the original P.
Also, although not shown, the reading unit 115 has incorporated therein LED""s (light emitting diodes) of three colors (red, green and blue) which are light sources for irradiating the original, an image sensor and a rod lens array for imaging the reflected light from the original on the light receiving element of the image sensor. The reading unit 115 changes over the LED""s of three colors in succession and turns on them (causes them to emit lights), and makes the image sensor read reflected lights produced from the original correspondingly to these lights, thereby effecting color resolution reading.
FIG. 7 is a plan view of the reading unit 115 contained in the image reading apparatus SC100 and various members concerned in the driving thereof as they are seen from the upper surface side as the internal structure of the apparatus.
As shown in FIG. 7, the frame 111 of the image reading apparatus SC100 has incorporated therein the reading unit 115, driving members such as a slider 102, a guide shaft 103 and a belt 104 for driving the reading unit, and an electrical portion 106 comprising a control board, a power source, etc.
The reading unit 115 is fixedly supported on the slider 102 sliding on the guide shaft 103 fixed to the main body of the apparatus SC100. Also, the belt 104 for transmitting motive power from a motor 105 which is a scanning drive source is fixed to the slider 102 or the unit 115. By the forward and reverse rotations of the motor 105, the scanning unit 115 is reciprocally moved in the glass plane area of the original supporting glass plate 100 (see FIG. 6) along the axis of the guide shaft 102. Thus, the image on the original P is read.
Now, as is apparent from the foregoing description, in the image reading apparatus according to the prior art, the drive source for moving the reading unit (scanning member) is provided at a predetermined location (in the above-described example of the prior art, the bottom) in the main body of the image reading apparatus, discretely from the scanning member.
Therefore, it has been necessary that a space for disposing the drive source therein should be secured somewhere in the main body of the apparatus except the movement area of the image sensor. Moreover, it also becomes necessary to dispose the driving members such as the belt, etc. from the drive source and therefore, the downsizing of the apparatus has naturally been limited.
Against such a problem, it has also been conceived to achieve the downsizing of the apparatus by adopting a construction in which the drive source (the motor or the like) for the scanning member is contained in or attached to the scanning member to thereby move the scanning member by its own ability without the intermediary of an extraneous driving motor or a motive power transmitting mechanism.
Now, if the drive source is provided in the scanning member, different machine parts such as the reading unit including the image sensor and the drive source are provided in the scanning member. Thereupon the connection between electrical signal paths necessary for the driving and control of the two becomes necessary and therefore, the number of the electrical signal paths is increased to thereby complicate the wiring. Further, to accomplish highly accurate image reading, it is indespensable for the operation of the scanning member to be effected with high accuracy. With regard also to this point, the addition of the drive source increases the number of the parts of the scanning member and in addition, it is undeniable that the complication of the wiring of the electrical signal paths would become disadvantageous for the reliability of the scanning operation of the scanning member.
The present invention has been made in view of the above-noted problems, and an object thereof is to provide an image reading apparatus in which the movement of a scanning member can be effected smoothly.
Another object of the present invention is to provide an image reading apparatus of simple construction.
Still another object of the present invention is to provide an image reading apparatus comprising:
a scanning member movable along an original mounting table, the scanning member having a reading element for reading the image of an original, and a drive source for moving the scanning member;
a frame containing the scanning member therein; and
a cable for electrically connecting the scanning member and the frame side together, the cable having a first electrical signal path connected to the reading element, and a second electrical signal path connected to the drive source.